Claude Code hooks hot-reload into already-running sessions

Adding a Stop hook to ~/.claude/settings.json takes effect for sessions that were already running before the edit - no restart needed. Claude Code re-reads hook config rather than snapshotting it at session start, so an installer that wires hooks works immediately even in the terminal that ran it. Also useful: wrapper apps (like cmux) can inject additional hooks per-session via a merged --settings flag, so "Ran N stop hooks" in the UI counts theirs plus yours; only hooks that return decision:block produce visible text.